Water-soluble, uv-absorbing and/or flourescent components with very high isoelectric points

ABSTRACT

Water-soluble, UV-absorbing and/or fluorescing compound having an isoelectric point greater than 10, can be obtained using molecules chosen from the group of molecules consisting of those containing at least one secondary alcohol OH group with a PK a  value greater than 10 and at least one amino group with a pK b  value smaller than 5, those containing at least one primary alcohol OH group and at least one secondary alcohol OH group with respective PK a  values greater than 10 and at least one amino group with a pK b  value smaller than 5 or a quaternary ammonium group, and those containing at least two secondary alcohol OH groups with respective pK a  values greater than 10 and at least one amno group with a pK b  value smaller than 5 or a quaternary ammonium group; and having at least one UV absorbing group or at least one fluorescing group or a combination thereof. The invention includes methods for producing such compounds.

BACKGROUND OF THE INVENTION

1. Field

The invention is in the field of isoelectric focusing and compoundshaving isoelectric points (pI values) that are used as markers duringisoelectric focusing.

2. State of the Art

In isoelectric focusing, pI markers are needed to establish the courseof the pH gradient in which the separation occurs. Proteins with wellcharacterized pI values are frequently used as pI markers. However,proteins are hydrolytically and oxidatively unstable; degraded proteinshave pI values that are different from those of the original proteins.Therefore, attempts have been made to use well focusing small moleculesas pI markers, e.g., UV absorbing aminomethyl phenols and aminomethylnitrophenols [Slais, K., Friedl, Z., J. Chromatogr. A 661 (1994)249-256; Slais, Z. Friedl, J. Chromatogr. A 695 (1995) 113-122];fluorescein derivatives [Horka M, Willimann T, Blum M, Nording P, FriedlZ, Slais K., J. Chromatogr. A 916 (2001) 65-71; Slais K, Horka M,Novackova J, Friedl Z., Electrophoresis, 23 (2002) 1682-1688] andfluorescent tag-labeled tri- and tetrapeptides [Shimura K, Kamiya K,Matsumoto H, Kasai K, Anal. Chem. 74 (2002) 1046-1053]. A small moleculeis considered a well focusing marker when the absolute value of thedifference between its pI value and its pK_(a) value closest to the pIvalue is less than 1. Unfortunately, these small molecule pI markers areavailable only in a limited pI range, typically from 3<pI<10.5, andoften have poor aqueous solubilities which limit their applications.

For accurate characterization of very basic proteins, it would bedesirable to have UV absorbing or fluorescing, water soluble pI markersfor the 10.5<pI range as well. Unfortunately, such pI markers are notavailable due to the pK_(a) limitation of amines.

SUMMARY OF THE INVENTION

According to the invention, water-soluble, UV-absorbing and/orfluorescing compound having an isoelectric point greater than 10, can beobtained using molecules chosen from the group of molecules consistingof those containing at least one secondary alcohol OH group with apK_(a) value greater than 10 and at least one amino group with a pK_(b)value smaller than 5, those containing at least one primary alcohol OHgroup and at least one secondary alcohol OH group with respective pK_(a)values greater than 10 and at least one amino group with a pK_(b) valuesmaller than 5 or a quaternary ammonium group, and those containing atleast two secondary alcohol OH groups with respective pK_(a) valuesgreater than 10 and at least one amino group with a pK_(b) value smallerthan 5 or a quaternary ammonium group; and having at least one UVabsorbing group or at least one fluorescing group or a combinationthereof.

We have found that the pK_(a) values of the secondary alcohol groups ofcertain carbohydrates and polyhydroxy compounds lie in the10.5<pK_(a)<13.5 range, while the pK_(a) values of the primary alcoholgroups are typically in the pK_(a)>13.5 range. For example, the pK_(a)values for the secondary alcohol OH group of the native cyclodextrinsare as follows: α-CD: 12.05; β-CD: 12.20; γ-CD: 12.33. The pKa valuesfor the secondary alcohol OH group of a few simple carbohydrates are asfollows: maltose: 11.94; mannose: 12.08; glucose: 12.28; dulcitol:13.43; sorbitol: 13.60.

By creating a molecule that contains at least one such secondary alcoholOH group with a 10.5<pK_(a)<13.5 and an amine group with a 1<pK_(b)<4 orat least two such secondary alcohol OH groups with pK_(a) values in the10.5<pK_(a)<13.5 range and one strong electrolyte cationic group (suchas a quaternary ammonium group) or at least one such secondary alcoholOH group with a pK_(a) value in the 10.5<pK_(a)<13.5 range and one suchprimary alcohol OH group with a pK_(a) value in the 13<pK_(a) range andone strong electrolyte cationic functional group (such as a quaternaryammonium group), an isoelectric substance with a high pI value can beformed. If a UV absorbing or fluorescing functional group is attached tosuch an isoelectric substance such that the material remains soluble inwater, small molecule pI markers for the 10<pI range are created.

We have also found that the secondary alcohols of many oligo- andpolysaccharides including, but not restricted to, cyclodextrins,maltodextrins, amyloses, starches, celluloses, guar gums, etc., have thesame desired property (alcoholic OH groups with pKa values in the10.5<pK_(a)<13.5 range) and these oligomers and/or polymers can bemodified with suitable amine or quaternary ammonium functional groups tocreate high pI isoelectric materials which can be converted into UVabsorbing or fluorescing, water soluble pI markers with 10<pI values.

Furthermore, we have found that the secondary alcohol groups of manyoligomeric and polymeric materials including, but not restricted to,poly(vinyl alcohol) and its derivatives, partially or fully hydrolyzedpoly(epihalohydrine)s and their derivatives, polymers formed from mono-,di-, oligo- or polyepoxides also have the same desired properties(alcoholic OH groups with pK_(a) values in the 10.5<pK_(a)<13.5 range)and these oligomers and/or polymers can be modified with suitable amineor quaternary ammonium functional groups to create high pI isoelectricmaterials that subsequently can be converted into UV absorbing orfluorescing, water soluble pI markers with 10<pI values.

Apart from serving as pI markers, many additional tasks can be solvedutilizing the UV-absorbing and/or fluorescing compounds that have veryhigh isoelectric points (pI values) and high aqueous solubilitieswithout departing from the essence of this disclosure. For example, theycan also be used as cathodic blocking agents in both imaging andsingle-point detection capillary isoelectric focusing systems asdescribed in copending U.S. application Ser. No. 10/763,981,incorporated herein by reference.

The invention also includes the method of making a water-soluble,UV-absorbing and/or fluorescing compound having an isoelectric pointgreater than 10, by obtaining molecules chosen from the group ofmolecules consisting of those containing at least one secondary alcoholOH group with a pK_(a) value greater than 10, those containing at leastone primary alcohol OH group and at least one secondary alcohol OH groupwith respective pK_(a) values greater than 10, and those containing atleast two secondary alcohol OH groups with respective pK_(a) valuesgreater than 10; attaching to such molecules at least one amino grouphaving a pK_(b) value smaller than 5 selected from the group consistingof primary amino, secondary amino, tertiary amino and quaternary ammoniogroups; and attaching at least one UV absorbing group or at least onefluorescing group or a combination thereof.

An alternate method comprises obtaining molecules chosen from the groupof molecules consisting of those containing at least one secondaryalcohol OH group with a pK_(a) value greater than 10 and at least oneamino group with a pK_(b) value smaller than 5, those containing atleast one primary alcohol OH group and at least one secondary alcohol OHgroup with respective pK_(a) values greater than 10 and at least oneamino group with a pK_(b) value smaller than 5 or a quaternary ammoniumgroup, and those containing at least two secondary alcohol OH groupswith respective pK_(a) values greater than 10 and at least one aminogroup with a pK_(b) value smaller than 5 or a quaternary ammonio group;and attaching to such molecules at least one UV absorbing group or atleast one fluorescing group or a combination thereof.

A further alternate method of making a water-soluble, UV-absorbingand/or fluorescing compound having an isoelectric point greater than 10,comprises obtaining molecules chosen from the group of moleculesconsisting of those containing at least a UV absorbing group or afluorescing group or a combination thereof, and at least one secondaryalcohol OH group with a pK_(a) value greater than 10 or at least oneprimary alcohol OH group and at least one secondary alcohol OH groupwith respective pK_(a) values greater than 10 or at least two secondaryalcohol OH groups with respective pK_(a) values greater than 10; andattaching to such molecules at least one amino group having a pK_(b)value smaller than 5 selected from the group consisting of primaryamino, secondary amino, tertiary amino or quaternary ammonio groups orcombinations thereof.

A still further alternate method of making a water-soluble, UV-absorbingand/or fluorescing compound having an isoelectric point greater than 10,comprises obtaining molecules chosen from the group of moleculesconsisting of those containing at least a UV absorbing group or afluorescing group or a combination thereof, and at least one amino grouphaving a pK_(b) value smaller than 5 selected from the group consistingof primary amino, secondary amino, tertiary amino or quaternary ammoniogroups or combinations thereof, and attaching at least one R groupwherein R contains at least one secondary alcohol OH group with a pK_(a)value greater than 10 or at least one primary alcohol OH group and atleast one secondary alcohol OH group with respective pK_(a) valuesgreater than 10 or at least two secondary alcohol OH groups withrespective pK_(a) values greater than 10 or combinations thereof.

THE DRAWING

In the accompanying drawing:

FIG. 1 is a graph showing an overlay of two runs of a three band PreMCE(pressure-mediated capillary electrophoretic) experiment usingmono(6-deoxy-6-pyridinium) -β-cyclodextrin (CDP) p-toluenesulfonate saltshowing cationic and anionic migration.

DETAILED DESCRIPTION OF EXAMPLES OF THE INVENTION

1. Synthesis of mono(6-deoxy-6-pyridinium)-β-cyclodextrin (CDP)p-toluenesulfonate salt

Mono(6-deoxy-6-pyridinium)-β-cyclodextrin p-toluenesulfonate salt, CDP,was synthesized from mono-6-O-tosyl β-CD and pyridine.Mono-6-O-tosyl-β-CD was obtained by adding 11.5 g (10 mmol) β-CD, 4.9 g(15 mmol) tosyl anhydride and 250 mL deionized water to a 0.5 L roundbottom flask. After stirring at ambient temperature for 2 hours, 5 gNaOH in 50 mL deionized water was added and the unreacted tosylanhydride was filtered off after 10 min, followed by the addition of13.4 g of NH₄Cl to precipitate mono-6-O-tosyl-β-CD that was washed withwater and acetone. The purity of the product was>98% mol/mol (HPLCanalysis with a 250 mm long, 4.6 mm I.D. column packed with 5 μm Lunasilica, Phenomenex, Torrence, Calif., USA, 70:30 ethylacetate: methanolas eluent and a flow rate of 2.0 mL/min).

250 mL dry pyridine was added to a 0.5 L three neck round bottom flask,purged with N₂, followed by the addition of 10 g mono-6-O-tosyl-β-CD.The reaction mixture was heated to 70° C. and stirred in a N₂ atmospherefor 48 hrs. Excess pyridine was evaporated, the residue was dissolved in60 mL deionized water, the undissolved solids were filtered off, about ⅔of water was evaporated and the remaining solution was dropped into 250mL acetone. A precipitate formed that was filtered off, redissolved inwater and reprecipitated with acetone. Dissolution and reprecipitationwas repeated three times, the product was dried in a vacuum oven atambient temperature and analyzed by capillary electrophoresis (CE), highresolution MALDI-TOF-MS and ¹H NMR.

Pressure-mediated capillary electrophoretic (PreMCE) analysis [Williams,B. A., Vigh, Gy., Anal. Chem., 68 (1996) 1174-1180] using backgroundelectrolytes (BGEs) that contained sodium carbonate and sodium hydroxideindicated that the pI value of CDP was in the 12<pI<12.3 range (videinfra).

The approximate pI values of ampholytes can be calculated from theireffective electrophoretic mobilities measured at different pH values inthe 11<pH<13.5 range. In a 3-band PreMCE experiment, a band of analyte Ais injected for t_(inj) (1 second) by low pressure on the P/ACE 5000instrument (Beckman-Coulter, Fullerton, Calif.). Next, pure BGE isinjected for a period of t_(transf) (30 seconds) by the same lowpressure to move analyte A into the capillary for distance l_(transf)(first transfer step). Next, neutral marker N1 is injected for t_(inj)(first neutral marker band, N1), then transferred into the capillary bypure BGE for l_(transf). Another band of neutral marker (second neutralmarker band, N2) is injected for time t_(inj) and transferred into thecapillary by pure BGE for l_(transf) resulting in bands of A, N1 and N2that are equidistant (l_(transf)) from each other in the capillary.Next, the band train is electrophoresed for t_(migr) at potentialU_(appl), with the anode at the injection end and the cathode at thedetector end of the capillary, followed by the injection of a thirdneutral marker band (push peak, P). Then, the entire band train ismobilized through the detector window by low pressure and the detectortrace is recorded.

The mobilization velocity, V_(mob) can be calculated from theinjector-to-detector distance, L_(d) and the mobilization time of thepush peak, t_(p). From v_(mob) and the time difference between themobilization times of N2 and N1, (t_(N2)-t_(N1)), one can calculate thetransfer distance, l_(transf). From v_(mob) and the time differencebetween the mobilization times of P and N2, (t_(P)-t_(N2)) one cancalculate the sum of l_(transf) and the distance migrated byelectroosmosis, l_(BO). Finally, from v_(mob) and the time differencebetween the mobilization times of N1 and A, (t_(N1)-t_(A)), one cancalculate the sum of l_(transf) and the effective electrophoreticmigration distance of A, l^(eff) _(A). From l^(eff) _(A), t_(migr) andthe field strength, E (E=U_(appl)/L_(t)), one can calculate theeffective electrophoretic mobility of the analyte, μ^(eff) _(A). Apositive sign for μ^(eff) _(A) means that the band of A migratescationically, a negative sign means that the band of A migratesanionically. The pH range over which the sign of μ^(eff) _(A) changesbrackets the pI value of analyte A.

The PreMCE technology can also be used to visually locate the pI rangeof analyte A. To do so, a 3-band PreMCE experiment is completed at aselected pH for the band sequence A, N1, N2. The detector trace of therun is displayed twice in the data analysis software: the second copy ofthe detector trace is shifted to align the peak centroid of N2 in thesecond copy of the trace with the peak centroid of N1 in the first copyof the same trace causing the peak centroid of N1 in the second copy ofthe trace to indicate the position, in the first copy of the trace,where the band of A was before electrophoresis (because l_(transf) isthe same for A and N1, and N1 and N2). When peak A in the first copy ofthe trace lies to the left of peak N1 in the second copy of the trace,the band of A migrated cationically. If it lies to the right, itmigrated anionically.

Using the 1-(3-sulfopropyl)pyridinium hydroxide, inner salt, as aneutral marker (N1, N2 and P), three band PreMCE experiments werecarried out with CDP in BGEs whose pH was increased in approximately0.2-0.3 units between pH=11 and pH=13.5. For the experiments with CDP,t_(inj)=1 s, t_(transf)=30 s, t_(migr)=4 min and U_(appl)=15 kV wereused. The runs were evaluated as described and the results from twoexperiments in which cationic and anionic migration was observed, wereoverlaid in FIG. 1. FIG. 1 indicates that 12.0<pI_(CDP)<12.3.

2. Synthesis of mono(6-deoxy-6-N,N-dimethylbenzylammonio)-β-cyclodextrinp-toluenesulfonate salt (CDMB)

Mono(6-deoxy-6-N,N-dimethylbenzylammonio)-β-cyclodextrinp-toluenesulfonate salt, CDMB, was synthesized using the proceduredescribed in Example 1 above, except that N,N-dimethylbenzylamine wasused as UV absorbing amine. The identity and purity of the product wasestablished by CE, high resolution MALDI-TOF-MS and ¹H NMR.

PreMCE analysis using background electrolytes that contained sodiumcarbonate and sodium hydroxide as described in Example 1 above indicatedthat the pI value of CDMB was in the 12<pI<12.5 range.

3. Synthesis ofmono(6-deoxy-6-(N,N,N′-trimethyl-N-3-propoxy-phenyl)ammonio)-β-cyclodextrinsalt (CDMPA)

Mono(6-deoxy-6-(N,N,N′-trimethyl-N-3-propoxy-phenyl)diammonio)-β-cyclodextrinsalt, CDMPA, was synthesized using the procedure described in Example 1,except that mono-6-O-tosyl-β-CD was first coupled withN,N,N′-trimethylamine in excess N,N,N′-trimethylamine as solvent. Theresulting tertiary diamine was converted into the mono-quatemaryammonium derivative by the UV absorbing chromophore, 3-phenoxypropylbromide, and the di-quaternary ammonium derivative by methyl iodide inDMF. The identity and purity of the product was established by CE, highresolution MALDI-TOF-MS, and ¹H and ¹³C NMR.

PreMCE analysis using background electrolytes that contained sodiumcarbonate and sodium hydroxide as described above in Example 1 indicatedthat the pI value of CDMPA was in the 11<pI<13 range.

4. Synthesis of N,N-dimethyl-N-(3-phenoxypropyl)-D-glucaminium bromide(DMPG)

N,N-dimethyl-N-(3-phenoxypropyl)-D-glucaminium bromide, DMPG wasobtained from N,N-dimethyl-D-glucamine and 3-phenoxypropyl bromide.N,N-dimethyl-D-glucamine was synthesized by carefully adding 6.79 g (128mmol) aqueous formic acid (88 % v/v) and 4.57 g (56.3 mmol) aqueousformaldehyde (37% v/v) into an iced-down 0.5 L round bottom flask thathad an attached Liebig condenser. After addition, the solution wasbrought to ambient temperature. 10.0 g (51.2 mmol) ofN-methyl-D-glucamine was added to the reaction mixture in portions, andwas then refluxed and stirred. After 16 hrs and cooling to ambienttemperature, 5.3 g concentrated HCl was added drop-wise to the flask andwater was removed by azeotrope vacuum distillation. The product wasrecrystallized from ethanol and vacuum dried to obtainN,N-dimethyl-D-glucamine, HCl salt. 30 mL anhydrous MeOH was cooled and1.17 g (50.9 mmol) freshly cleaned sodium metal was carefully dissolvedin it. 10.6 g of N,N-dimethyl-D-glucamine, HCl salt, was slurried in 50mL hot methanol, added to the methanolic sodium methoxide solution andrefluxed for 20 min. NaCl was filtered off and methanol was removedunder reduced pressure. The identity and purity of the intermediate wasestablished by CE, high resolution MALDI-TOF-MS, and ¹H and ¹³C NMR.

50 mL of isopropanol was added to a 0.5 L three-neck round bottom flask,5.0 g (23.9-mmol) N,N-dimethyl-D-glucamine was dissolved in it. 0.625 g(30 mmol) 3-phenoxypropyl bromide dissolved in 50 mL acetonitrile wasadded to it drop-wise and refluxed for 52-hrs. Then, the solvent wasremoved in vacuum, the oily residue was washed with acetonitrile andacetone, then chilled in a dry ice/acetone bath under reduced pressureyielding 5.2 g (51% m/m yield) white solid.

The reaction was monitored by indirect-UV detection CE using a 30 mMβ-alanine BGE titrated to pH 3.6 with p-toluenesulfonic acid. Theidentity and purity of the final product was established by CE, highresolution MALDI-TOF-MS, and ¹H and ¹³C NMR.

PreMCE analysis using background electrolytes that contained sodiumcarbonate and sodium hydroxide as described above indicated that the pIvalue of DMPG was in the 13.1<pI<13.5 range.

The water soluble, UV-absorbing pI markers of the invention with high pIvalues allow extension of the calibration range of the pH gradient inisoelectric focusing to values higher than pH 10. The markers can alsobe used as cathodic blockers for imaging isoelectric focusingseparations as described in copending U.S. application Ser. No.10/763,981. According to the method of that that application, theconcentration detection limit in capillary isoelectric focusing (CIEF)and imaging capillary isoelectric focusing (iCIEF) systems is improvedwhen the sample holding volume of the isoelectric focusing system isincreased by adding an auxiliary compartment to at least one end, andpreferably both ends, of the separation capillary, especially when theuse of an added auxiliary compartment is combined with the addition ofat least one auxiliary agent. The auxiliary agent is added so thatduring isoelectric focusing the auxiliary agent substantially forces theampholytic sample components from the auxiliary compartment into theseparation capillary where detection takes place. This increases theconcentration of the ampholytic sample components in the separationcapillary, thereby improving the concentration detection limit in thecapillary isoelectric focusing system. Adding an auxiliary agent withoutan auxiliary compartment will also work to improve the concentrationdetection limit, although not as effectively. The preferred auxiliaryagents are ampholytic compounds. When the auxiliary agent is anampholytic compound, it should have an isoelectric point either lowerthan or higher than the isoelectric points of all of the ampholyticcomponents of interest in the sample. The pI markers of this inventionwith high pI values are perfect for use as the auxiliary agents havingan isoelectric point higher than the isoelectric points of all of theampholytic components of interest in the sample.

Numerous other UV-absorbing or fluorescent, water soluble pI markersthat have high pI values could be made along the synthetic linesdescribed above, and these could be just as useful as the examplesdescribed here.

Whereas the invention is here illustrated and described with referenceto embodiments thereof presently contemplated as the best mode ofcarrying out the invention in actual practice, it is to be understoodthat various changes may be made in adapting the invention to differentembodiments without departing from the broader inventive conceptsdisclosed herein and comprehended by the claims that follow.

1. A water-soluble, UV-absorbing and/or fluorescing compound having anisoelectric point greater than 10, comprising: molecules: chosen fromthe group of molecules consisting of those containing at least onesecondary alcohol OH group with a pK_(a) value greater than 10 and atleast one amino group with a pK_(b) value smaller than 5, thosecontaining at least one primary alcohol OH group and at least onesecondary alcohol OH group with respective pK_(a) values greater than 10and at least one amino group with a pK_(b) value smaller than 5 or aquaternary ammonium group, and those containing at least two secondaryalcohol OH groups with respective pK_(a) values greater than 10 and atleast one amino group with a pK_(b) value smaller than 5 or a quaternaryammonium group; and having at least one UV absorbing group or at leastone fluorescing group or a combination thereof.
 2. A water-soluble,UV-absorbing and/or fluorescing compound according to claim 1, whereinthe molecule is selected from a group consisting of alcohols, diols,triols, tetraols and polyols.
 3. A water-soluble, UV-absorbing and/orfluorescing compound according to claim 1, wherein the molecule is acarbohydrate derivative.
 4. A water-soluble, UV-absorbing and/orfluorescing compound according to claim 1, wherein the molecule is acyclodextrin derivative.
 5. A water-soluble, UV-absorbing and/orfluorescing compound according to claim 1, wherein the molecule containsat least one primary amino or secondary amino or tertiary amino orquaternary ammonio group or combinations thereof.
 6. A water-soluble,UV-absorbing and/or fluorescing compound according to claim 1, whereinthe molecule contains at least one UV absorbing and/or fluorescing aryl,alkylaryl, alkoxyaryl or heteroaromatic functional group or combinationsthereof.
 7. A water-soluble, UV-absorbing and/or fluorescing compoundaccording to claim 1, wherein the at least one UV absorbing and/orfluorescing group in the molecule is selected from the group containingphenyl, alkylphenyl, alkoxyphenyl, hydroxyphenyl, alkyl(hydroxyphenyl),alkoxy(hydroxyphenyl), phenoxy, alkoxyphenoxy, hydroxyphenoxy,alkoxy(hydroxyphenoxy), naphthyl, alkylnaphthyl, alkoxynaphthyl,hydroxynaphthyl, alkyl(hydroxynaphthyl), alkoxy(hydroxynaphthyl),naphthoxy, alkoxynaphthoxy, hydroxynaphthoxy, alkoxy(hydroxynaphthoxy),pyridinium, alkylpyridinium, alkoxypyridinium, hydroxypyridinium,alkyl(hydroxypyridinium), alkoxy(hydroxypyridinium), pyridiniumoxy,(alkylpyridinium)oxy, (alkoxypyridinium)oxy, (hydroxypyridinium)oxy,(alkyl(hydroxypyridinium))oxy and (alkoxy(hydroxypyridinium))oxy groups.8. A method of making a water-soluble, UV-absorbing and/or fluorescingcompound having an isoelectric point greater than 10, comprising:obtaining molecules: chosen from the group of molecules consisting ofthose containing at least one secondary alcohol OH group with a pKavalue greater than 10, those containing at least one primary alcohol OHgroup and at least one secondary alcohol OH group with respective pK_(a)values greater than 10, and those containing at least two secondaryalcohol OH groups with respective pK_(a) values greater than 10;attaching at least one amino group having a pK_(b) value smaller than 5selected from the group consisting of primary amino, secondary amino,tertiary amino and quaternary ammonio groups; and attaching at least oneUV absorbing group or at least one fluorescing group or a combinationthereof.
 9. A method of making a water-soluble, UV-absorbing and/orfluorescing compound having an isoelectric point greater than 10,comprising: obtaining molecules: chosen from the group of moleculesconsisting of those containing at least one secondary alcohol OH groupwith a pKa value greater than 10 and at least one amino group with a pKbvalue smaller than 5, those containing at least one primary alcohol OHgroup and at least one secondary alcohol OH group with respective pKavalues greater than 10 and at least one amino group with a pKb valuesmaller than 5 or a quaternary ammonium group, and those containing atleast two secondary alcohol OH groups with respective pKa values greaterthan 10 and at least one amino group with a pKb value smaller than 5 ora quaternary ammonio group; and attaching at least one UV absorbinggroup or at least one fluorescing group or a combination thereof.
 10. Amethod of making a water-soluble, UV-absorbing and/or fluorescingcompound having an isoelectric point greater than 10, comprising:obtaining molecules: chosen from the group of molecules consisting ofthose containing at least a UV absorbing group or a fluorescing group ora combination thereof, and at least one secondary alcohol OH group witha pK_(a) value greater than 10 or at least one primary alcohol OH groupand at least one secondary alcohol OH group with respective pK_(a)values greater than 10 or at least two secondary alcohol OH groups withrespective pK_(a) values greater than 10; and attaching at least oneamino group having a pK_(b) value smaller than 5 selected from the groupconsisting of primary amino, secondary amino, tertiary amino orquaternary ammonio groups or combinations thereof.
 11. A method ofmaking a water-soluble, UV-absorbing and/or fluorescing compound havingan isoelectric point greater than 10, comprising: obtaining molecules:chosen from the group of molecules consisting of those containing atleast a UV absorbing group or a fluorescing group or a combinationthereof, and at least one amino group having a pK_(b) value smaller than5 selected from the group consisting of primary amino, secondary amino,tertiary amino or quaternary ammonio groups or combinations thereof; andattaching at least one R group wherein R contains at least one secondaryalcohol OH group with a pK_(a) value greater than 10, or at least oneprimary alcohol OH group and at least one secondary alcohol OH groupwith respective pK_(a) values greater than 10, or at least two secondaryalcohol OH groups with respective pK_(a) values greater than 10, orcombinations thereof.